Activated carbon is porous and has advantages of large BET specific surface area, high adsorbability, desulfation, debenzoation, deodorization and decoloration properties. Moreover, the activated carbon can remove some specific constituents from liquid or gaseous medium.
Silver has the feature of antibacterial property. Colloidal silver, which includes tiny silver particles with diameter in a range of 10-100 nanometers, or nanosilver, developed recently, and is widely applied in many antiseptic products. For example, the colloidal silver is used as the antibacterial agent before penicillins were discovered, which can kill many kinds of microbes that are resistant to penicillins. According to recent research reports, nanosilver particles can easily attach with cell membrane or cell wall of a bacterium due to the positive charge on the surface of silver particle, and easily enter inside the bacterium and combine with the thiol (—SH) group, which is essential in aerobic metabolism. Therefore, the nanosilver can disrupt or retard the metabolism of the bacterium and inhibit the bacterium without adversely harming the host.
The combination of the activated carbon and silver particles provides the advantages of high adsorbability and high antiseptic ability, and has been used in products of many fields. The activated carbon and silver particles provides an excellent inorganic antiseptic without the problems of drug resistance. However, the silver particles used in activated carbon with silver content are not nanometric level such that the silver particles on surfaces of the activated carbon to have disadvantage of low efficient bacteriostasis. For enhancing the bacteriostasis, the silver content on the activated carbon is raised, but that also gets a side effect of polluting the environment and degrading the quality of water due to the escape of the silver on the activated carbon.